Operating system - Question and Answers - 3

11. What is kernel ?
DescriptionThe kernel is a computer program at the core of a computer's operating system with complete control over everything in the system. It is an integral part of any operating system. It is the "portion of the operating system code that is always resident in memory".
There are five types of kernels:

  1. A micro kernel, which only contains basic functionality.
  2. A monolithic kernel, which contains many device drivers.
  3. Hybrid Kernel.
  4. Exo Kernel.
  5. Nano Kernel.

12. Explain Round-robin algorithms ?
Round Robin is a CPU scheduling algorithm in which each process is assigned a fixed time slot in a cyclic way. It is a simple, easy to implement algorithm , and starvation-free as all processes get fair share of CPU.

13. What is Banker algorithm ?
The Banker algorithm, sometimes referred to as the detection algorithm, is a resource allocation and deadlock avoidance algorithm developed by Edsger Dijkstra that tests for safety by simulating the allocation of predetermined maximum possible amounts of all resources, and then makes an "s-state" check to test for possible deadlock conditions for all other pending activities, before deciding whether allocation should be allowed to continue.

14. What is Fragmentation ?
In computer storage, fragmentation is a phenomenon in which storage space is used inefficiently, reducing capacity or performance and often both. The exact consequences of fragmentation depend on the specific system of storage allocation in use and the particular form of fragmentation. In many cases, fragmentation leads to storage space being "wasted", and in that case the term also refers to the wasted space itself.When a computer program requests blocks of memory from the computer system, the blocks are allocated in chunks. When the computer program is finished with a chunk, it can free the chunk back to the system, making it available to later be allocated again to another or the same program. The size and the amount of time a chunk is held by a program varies. During its lifespan, a computer program can request and free many chunks of memory.

15. What is Multitasking ?
Multitasking, in an operating system, is allowing a user to perform more than one computer task (such as the operation of an application program) at a time. The operating system is able to keep track of where you are in these tasks and go from one to the other without losing information. In short multitasking is the concurrent execution of multiple tasks over a certain period of time. 
1 2 3 4 5 6 7